1. Field of the Invention
This invention relates to computer systems employing data communication busses and more particularly to power management of computer systems employing data communication busses.
2. Description of the Related Art
An ongoing developmental goal of manufacturers has been to reduce the power consumption of computer systems. Reducing power consumption typically reduces heat generation of the system, thereby increasing reliability and decreasing costs. In addition, reducing power consumption has been particularly important in maximizing the operating life of battery powered portable computer systems. Battery powered portable computer systems include personal information devices ("PIDs"), pocket personal computers, digital assistance, smart phones, and electronic calendars, organizers, booklets, etc.
Computer systems typically include data communication busses for interfacing to devices external to the processor and/or the computer system. These data communication busses allow for the efficient transfer of data between components of computer systems and provide a standardized interface to which different components may be designed. For example, a processor may include a bus interface unit (or bus bridge) that provides an interface to input/output devices.
One problem associated with typical bus interface units is the data buffers of the bus interface are clocked by the internal clock circuitry even though data is not actually being transmitted or received by the buffers. As a result, power is wasted when the buffers are in idle state. This is particularly problematic in bus interface units employed within battery powered portable computer systems.